linux-kernel - Re: [PATCH v3 2/3] dt-bindings: dma: ti-edma: Document dma-channel-mask for EDMA

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Message-ID: <20190927204854.GA20463@bogus>
Date:   Fri, 27 Sep 2019 15:48:54 -0500
From:   Rob Herring <robh@...nel.org>
To:     Peter Ujfalusi <peter.ujfalusi@...com>
Cc:     vkoul@...nel.org, dmaengine@...r.kernel.org,
        linux-kernel@...r.kernel.org, dan.j.williams@...el.com,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v3 2/3] dt-bindings: dma: ti-edma: Document
 dma-channel-mask for EDMA

On Thu, Sep 26, 2019 at 02:19:53PM +0300, Peter Ujfalusi wrote:
> Similarly to paRAM slots, channels can be used by other cores.
> 
> The common dma-channel-mask property can be used for specifying the
> available channels.
> 
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
> ---
>  Documentation/devicetree/bindings/dma/ti-edma.txt | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/dma/ti-edma.txt b/Documentation/devicetree/bindings/dma/ti-edma.txt
> index 4bbc94d829c8..014187088020 100644
> --- a/Documentation/devicetree/bindings/dma/ti-edma.txt
> +++ b/Documentation/devicetree/bindings/dma/ti-edma.txt
> @@ -42,6 +42,11 @@ Optional properties:
>  - ti,edma-reserved-slot-ranges: PaRAM slot ranges which should not be used by
>  		the driver, they are allocated to be used by for example the
>  		DSP. See example.
> +- dma-channel-mask: Mask of usable channels.
> +		Single uint32 for EDMA with 32 channels, array of two uint32 for
> +		EDMA with 64 channels. See example and
> +		Documentation/devicetree/bindings/dma/dma-common.yaml
> +
>  
>  ------------------------------------------------------------------------------
>  eDMA3 Transfer Controller
> @@ -91,6 +96,9 @@ edma: edma@...00000 {
>  	ti,edma-memcpy-channels = <20 21>;
>  	/* The following PaRAM slots are reserved: 35-44 and 100-109 */
>  	ti,edma-reserved-slot-ranges = <35 10>, <100 10>;
> +	/* The following channels are reserved: 35-44 */
> +	dma-channel-mask = <0xffffffff>, /* Channel 0-31 */
> +			   <0xffffe007>; /* Channel 32-63 */

Doesn't matter yet, but you have a mismatch here with the schema. While 
the <> around each int or not doesn't matter for the dtb, it does for 
the schema.

dma-channel-mask = <0xffffffff>, <0xffffe007>;
minItems: 1
maxItems: 255

dma-channel-mask = <0xffffffff 0xffffe007>;
items:
  minItems: 1
  maxItems: 255

I think the latter case is slightly more logical here as you have 1 
thing (a mask). If had N of something (like interrupts), then the former 
makes sense. 

Rob